Light-emitting device

ABSTRACT

A light-emitting device includes a substrate comprising a base member, a first wiring, a second wiring, and a via hole; at least one light-emitting element electrically connected to and disposed on the first wiring; and a covering member having light reflectivity and covering a lateral surface of the light-emitting element and a front surface of the substrate. The base member defines a plurality of depressed portions separated from the via hole in a front view and opening on a back surface and a bottom surface of the base member. The substrate includes a third wiring covering at least one of inner walls of the plurality of depressed portions and electrically connected to the second wiring. A depth of each of the plurality of depressed portions defined from the back surface toward the front surface is larger on a bottom surface side than on an upper surface side of the base member.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. patent application Ser. No.15/965,415, filed Apr. 27, 2018, which claims priority to JapanesePatent Application No. 2017-089996 filed on Apr. 28, 2017, No.2017-098438 filed on May 17, 2017, No. 2017-123949 filed on Jun. 26,2017, No. 2017-138720 filed on Jul. 18, 2017, No. 2017-203159 filed onOct. 20, 2017, the disclosures of which are hereby incorporated byreference in their entirety.

BACKGROUND

The present disclosure relates to a light-emitting device.

Light-emitting devices are known in which depressions are formed on themounting surfaces of supporting members (i.e., base members) and inwhich the supporting members (i.e., base members) are fixed to mountingboards by supplying brazing filler metals into the depressions (forexample, see Japanese Unexamined Patent Application Publication No.2013-041865).

The present disclosure has an object to provide a light-emitting devicein which the mechanical strength of a base member is less likely to bedecreased and the bonding strength to a mounting board is improved.

SUMMARY

A light-emitting device according to an embodiment of the presentdisclosure includes a substrate, at least one light-emitting element, acovering member. The substrate includes a base member having a frontsurface, a back surface, a bottom surface and an upper surface. Thefront surface extends in a first direction and a second direction. Thefirst direction is a longitudinal direction and the second is a widthdirection of the base member. The back surface opposite to the frontsurface. The bottom surface and the upper surface adjacent andperpendicular to the front surface while being opposed to each other.The substrate includes a first wiring disposed on the front surface anda second wiring disposed on the back surface; and a via holeelectrically connecting the first wiring and the second wiring. The atleast one light-emitting element is electrically connected to anddisposed on the first wiring. The covering member has light reflectivityand covers a lateral surface of the light-emitting element and a frontsurface of the substrate. The base member defines a plurality ofdepressed portions that are separated from the via hole in a front viewand are open on the back surface and the bottom surface. The substrateincludes a third wiring that covers at least one of inner walls of theplurality of depressed portions and electrically connects to the secondwiring. A depth of each of the plurality of depressed portions definedfrom the back surface toward the front surface is larger on a bottomsurface side than on an upper surface side of the base member.

In the present disclosure, a light-emitting device with alleviateddecrease in the mechanical strength of a base member and improvedbonding strength to a mounting board can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a first schematic perspective view of a light-emitting deviceaccording to a first embodiment.

FIG. 1B is a second schematic perspective view of the light-emittingdevice according to the first embodiment.

FIG. 1C is a schematic front view of the light-emitting device accordingto the first embodiment.

FIG. 2A is a schematic sectional view taken along the line 2A-2A in FIG.1C.

FIG. 2B is a schematic sectional view taken along the line 2B-2B in FIG.1C.

FIG. 3A is a schematic bottom view of the light-emitting deviceaccording to the first embodiment.

FIG. 3B is a schematic bottom view of a modification of thelight-emitting device according to the first embodiment.

FIG. 3C is a schematic front view of a base member according to thefirst embodiment.

FIG. 4A is a schematic back view of the light-emitting device accordingto the first embodiment.

FIG. 4B is a schematic back view of a modification of the light-emittingdevice according to the first embodiment.

FIG. 4C is a schematic back view of a modification of the light-emittingdevice according to the first embodiment.

FIG. 4D is a schematic bottom view of a modification of thelight-emitting device according to the first embodiment.

FIG. 4E is a schematic bottom view of a modification of thelight-emitting device according to the first embodiment.

FIG. 4F is a schematic bottom view of a modification of thelight-emitting device according to the first embodiment.

FIG. 5A is a schematic right side view of the light-emitting device inFIG. 1A according to the first embodiment.

FIG. 5B is a schematic left side view of the light-emitting device inFIG. 1A according to the first embodiment.

FIG. 6 is a schematic top view of the light-emitting device according tothe first embodiment.

FIG. 7 is a schematic front view of a light-emitting device according toa second embodiment.

FIG. 8A is a schematic sectional view taken along the line 8A-8A in FIG.7.

FIG. 8B is a schematic sectional view taken along the line 8B-8B in FIG.7.

FIG. 9A is a schematic bottom view of the light-emitting deviceaccording to the second embodiment.

FIG. 9B is a schematic back view of the light-emitting device accordingto the second embodiment.

FIG. 10 is a schematic front view of a light-emitting device accordingto a third embodiment.

FIG. 11 is a schematic sectional view taken along the line 11A-11A inFIG. 10.

FIG. 12 is a schematic bottom view of the light-emitting deviceaccording to the third embodiment.

FIG. 13 is a schematic back view of the light-emitting device accordingto the third embodiment.

FIG. 14 is a schematic right side view of the light-emitting deviceaccording to the third embodiment as seen from the front surface of thelight-emitting device.

FIG. 15 is a schematic front view of a modification of thelight-emitting device according to the third embodiment.

FIG. 16 is a schematic sectional view taken along the line 15A-15A inFIG. 15.

FIG. 17 is a schematic front view of a light-emitting device accordingto a fourth embodiment.

FIG. 18 is a schematic sectional view taken along the line 18A-18A inFIG. 17.

FIG. 19 is a schematic bottom view of the light-emitting deviceaccording to the fourth embodiment.

FIG. 20 is a schematic back view of the light-emitting device accordingto the fourth embodiment.

FIG. 21 is a schematic right side view of the light-emitting deviceaccording to the fourth embodiment.

FIG. 22 is a schematic back view of a light-emitting device according toa fifth embodiment.

FIG. 23 is a schematic back view of a light-emitting device according toa sixth embodiment.

FIG. 24 is a schematic back view of a light-emitting device according toa seventh embodiment.

FIG. 25A is a schematic bottom view of lands indicated by continuouslines and the light-emitting device according to the first embodimentindicated by dotted lines.

FIG. 25B is a schematic bottom view of a modification of lands indicatedby continuous lines and the light-emitting device according to the firstembodiment indicated by dotted lines.

FIG. 25C is a schematic bottom view of a modification of lands indicatedby continuous lines and the light-emitting device according to the firstembodiment indicated by dotted lines.

FIG. 26A is a schematic bottom view of lands indicated by continuouslines and the light-emitting device according to the fourth embodimentindicated by dotted lines.

FIG. 26B is a schematic bottom view of a modification of lands indicatedby continuous lines and the light-emitting device according to thefourth embodiment indicated by dotted lines.

FIG. 27 is a schematic front view of a light-emitting device accordingto an eighth embodiment.

FIG. 28A is a schematic sectional view taken along the line 28A-28A inFIG. 27.

FIG. 28B is a schematic sectional view taken along the line 28B-28B inFIG. 27.

FIG. 29 is a schematic bottom view of the light-emitting deviceaccording to the eighth embodiment.

FIG. 30 is a schematic back view of the light-emitting device accordingto the eighth embodiment.

FIG. 31 is a schematic sectional view of a modification of thelight-emitting device according to the eighth embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

The following describes embodiments of the disclosure with reference tothe accompanying drawings as appropriate. Light-emitting devicesdescribed below are intended to embody the technical concept of thepresent invention and do not limit the present invention to the devicesbelow unless specifically stated otherwise. It is noted that there is acase where magnitudes or positional relations of members illustrated inthe drawings may be exaggerated in order to clarify the descriptions.

First Embodiment

A light-emitting device 1000 according to an embodiment of the presentdisclosure will be described on the basis of FIG. 1A to FIG. 6. Thelight-emitting device 1000 includes a substrate 10, one or morelight-emitting elements 20, and a covering member 40. The substrate 10includes a base member 11, first wirings 12, second wirings 13, thirdwirings 14, and via holes 15. The base member 11 has a front surface 111extending in a first direction, which is the longitudinal direction, andin a second direction, which is the width direction; a back surface 112opposite to the front surface; and a bottom surface 113 and an uppersurface 114 both adjacent and perpendicular to the front surface 111while being opposed to each other; and at least one lateral surfacepositioned between the front surface and the back surface, and betweenthe upper surface and the bottom surface. The base member 11 furtherincludes a plurality of depressed portions 16. The first wirings 12 aredisposed on the front surface 111 of the base member 11. The secondwirings 13 are disposed on the back surface 112 of the base member 11.The via holes 15 electrically connect the first wirings 12 and thesecond wirings 13. The light-emitting elements 20 are electricallyconnected to and disposed on the first wirings 12. The covering member40 has a light-reflectivity and covers lateral surfaces 202 of thelight-emitting elements 20 and the front surface 111 of the substrate.The depressed portions 16 are separated from the via holes 15 in a frontview, and open on the back surface 112 and the bottom surface 113. Thethird wirings 14 cover the inner walls of the depressed portions 16, andare electrically connected to the second wirings 13. Each of thedepressed portions 16 has depths W1 and W2 from the back surface 112toward the front surface 111. The depth W1 which is positioned on thebottom surface side is larger than a depth W2 which is positioned on theupper surface side. The term “perpendicular” in the presentspecification means 90°±3°.

The light-emitting device 1000 can be fixed to a mounting board withbonding members, such as solder, formed inside the depressed portions16. The bonding members can be located in the depressed portions, andtherefor, the bonding strength between the light-emitting device 1000and the mounting board can be improved compared with the case where onlyone depressed portion is formed. As shown in FIG. 2A, the depth of eachof the depressed portions from the back surface toward the front surface(in the Z direction) is larger on the bottom surface side than on theupper surface side, thereby allowing a thickness W5 of the base memberon the upper surface side of the depressed portion to be larger than athickness W6 of the base member on the bottom surface side of thedepressed portion in the direction (i.e., Z direction) from the backsurface toward the front surface. This structure can alleviate decreasein the strength of the base member. Also, making the depth W1 of thedepressed portion on the bottom surface side large can increase volumeof the bonding member formed inside the depressed portion, therebyimprovement of the bonding strength between the light-emitting device1000 and the mounting board. Increase in the volume of the bondingmember can improve the bonding strength to the mounting board in bothtype of a top view light-emitting device and a side view light-emittingdevice. The top-view type of light-emitting device is mounted such thatthe back surface 112 of the base member 11 faces the mounting board. Theside-view type of light-emitting device is mounted such that the bottomsurface 113 of the base member 11 faces the mounting board. In thepresent specification, the direction from the back surface toward thefront surface is also referred to as the Z direction.

The bonding strength between the light-emitting device 1000 and themounting board can be improved particularly in the case of the side-viewtype. The depth of the depressed portions in the Z direction is largeron the bottom surface side than on the upper surface side, the area ofthe opening of the depressed portion on the bottom surface becomeslarge. Increase in the area of the opening of the depressed portion onthe bottom surface, which faces the mounting board, increases the areaof the bonding member located on the bottom surface. This can increasethe area of the bonding member located on the surface facing themounting board, thereby improving the bonding strength between thelight-emitting device 1000 and the mounting board.

As shown in FIG. 2A, the depth W1 of the depressed portion 16 in the Zdirection is smaller than a thickness W3 of the base member in the Zdirection. In other words, the depressed portion 16 does not penetratethrough the base member. Forming a hole penetrating through the basemember reduces the strength of the base member. Hence, forming thedepressed portion that does not penetrate through the base member canalleviate decrease in the strength of the base member. The maximum depthof each of the depressed portions in the Z direction is preferably 0.4to 0.8 times as large as the thickness of the base member. If the depthof the depressed portion is larger than 0.4 times the thickness of thebase member, the volume of the bonding member formed inside thedepressed portion increases, thereby improving the bonding strengthbetween the light-emitting device and the mounting board. If the depthof the depressed portion is smaller than 0.8 times the thickness of thebase member, decrease in the strength of the base member can bealleviated.

In a sectional view, the depressed portion 16 preferably includes aparallel portion 161 extending from the back surface 112 in thedirection (i.e., Z direction) parallel to the bottom surface 113. If theparallel portion 161 is included, the capacity of the depressed portionbecomes larger even with the same area of the opening of the depressedportion on the back surface. Increasing the capacity of the depressedportion can increase the amount of the bonding member, such as solder,formed inside the depressed portion, thereby improving the bondingstrength between the light-emitting device 1000 and the mounting board.The term “parallel” in the present specification means that tolerance ofan inclination of about ±3° is acceptable. In a sectional view, thedepressed portion 16 has an inclined portion 162 inclined from thebottom surface 113 toward the direction in which the thickness of thebase member 11 increases. The inclined portion 162 may be linear orcurved. If the inclined portion 162 is linear, the inclined portion 162can be readily formed with a drill having a pointed tip. The term“linear” regarding the inclined portion 162 means that a variation suchas a curve and a deviation of about 3 μm is acceptable.

On the bottom surface, the depth W1 at the center of each of thedepressed portions 16 is preferably the maximum depth of the depressedportion in the Z direction as shown in FIG. 3A. With this structure, thethickness W8 of the base member in the Z direction can be increased atthe end of the depressed portion in the X direction on the bottomsurface, thereby improving the strength of the base member. The term“center” in the present specification means that a tolerance of about 5μm is acceptable. A depth W7 of the depressed portion 16 on the bottomsurface may be substantially constant in the Z direction as shown inFIG. 3B showing a modification of the first embodiment. In other words,the deepest portion of the depressed portion 16 may be a flat surface.The depressed portion 16 can be formed by a known method, for example, adrill or laser. The depressed portion that has deepest portion at thecenter on the bottom surface can be easily formed with a drill having apointed tip. With a drill, a depressed portion having a substantiallyconical deepest portion and a substantially cylindrical portioncontinuous with the circle of the bottom surface of the substantiallyconical shape can also be formed. A depressed portion having asubstantially semiconical deepest portion and a substantiallysemicolumnar portion continuous with the substantial semicircle can beformed by cutting part of the depressed portion by dicing or the like.

The depressed portions 16 preferably have the same shape on the backsurface as shown in FIG. 4A. If the depressed portions have the sameshape as each other, the depressed portions are more easily formed thanin the case where the depressed portions have different shapes. Forexample, in the case where the depressed portions are formed bydrilling, the depressed portions having the same shape as each other canbe formed with one drill. The term “same” in the present specificationmeans that a tolerance of about 5 μm is acceptable.

The areas of the openings of the depressed portions in a back view maybe the same as or different from each other. For example, in a backview, the opening of a depressed portion 16C located at the center ofthe base member may has the area larger than the area of the opening ofeach of a depressed portion 16L located on the X+ side and a depressedportion 16R located on the X− side as shown in FIG. 4B. In back viewsshown in FIG. 4B, FIG. 4C, and the like, the right side of the center ofthe light-emitting device in the X axis is referred to as the X+ side,and the left side is referred to as the X− side. Increasing the area ofthe opening of the depressed portion 16C located at the center of thebase member can improve the bonding strength between the light-emittingdevice and the mounting board. Also, decreasing the areas of theopenings of the depressed portion 16L located on the X+ side and thedepressed portion 16R located on the X− side makes it easy to increasethe areas of the second wirings 13. If the areas of the second wirings13 are large, inspections can be easily performed in the case where aprobe needle is brought into contact with the second wirings in thecharacteristic inspection or the like of the light-emitting device.Also, in a back view, the area of the opening of each of the depressedportion 16L located on the X+ side and the depressed portion 16R locatedon the X− side may be larger than the area of the opening of thedepressed portion 16C located at the center of the base member as shownin FIG. 4C. Increasing the area of the opening of each of the depressedportion 16L located on the X+ side and the depressed portion 16R locatedon the X− side can improve the bonding strength between thelight-emitting device and the mounting board. Also, in a back view, itis preferable that the areas of the openings of the depressed portion16L located on the X+ side and the depressed portion 16R located on theX− side be substantially the same with each other. This structure canalleviate a mass imbalance between a bonding member formed inside thedepressed portion 16L located on the X+ side and a bonding member formedinside the depressed portion 16R located on the X− side. Accordingly,the light-emitting device is less likely to be inclined after beingmounted on the mounting board.

The depths of the depressed portions in the Z direction may be the sameas shown in the depths W1 of FIG. 3A or the depths W7 of FIG. 3B.Alternatively, the depths of the depressed portions in the Z directionmay be different as shown in FIG. 4D. For example, in a bottom view, adepth W1C in the Z direction of the depressed portion 16C located at thecenter of the base member may be larger than a depth W1L in the Zdirection of the depressed portion 16L located on the X+ side and adepth W1R in the Z direction of the depressed portion 16R located on theX− side as shown in FIG. 4D. In bottom views shown in FIG. 4D, FIG. 4E,and FIG. 4F, the left side of the center of the light-emitting devicealong the X axis is referred to as the X+ side, and the right side isreferred to as the X− side. Increasing the depth W1C of the depressedportion 16C located at the center of the base member can improve thebonding strength between the light-emitting device and the mountingboard. In a bottom view, the depth W1L in the Z direction of thedepressed portion 16L located on the X+ side and the depth W1R in the Zdirection of the depressed portion 16R located on the X− side may belarger than the depressed portion W1C in the Z direction of thedepressed portion 16C located at the center of the base member. Also, itis preferable that the depth W1L in the Z direction of the depressedportion 16L located on the X+ side is substantially the same as thedepth W1R in the Z direction of the depressed portion 16R located on theX− side. This structure facilitates reduction in a mass imbalancebetween the bonding member formed inside the depressed portion locatedon the X+ side and the bonding member formed inside the depressedportion located on the X− side. Accordingly, the light-emitting deviceis less likely to be inclined after being mounted on the mounting board.

In a bottom view, a width D1C in the X direction of the depressedportion 16C located at the center of the base member, a width D1L in theX direction of the depressed portion 16L located on the X+ side, and awidth D1R in the X direction of the depressed portion 16R located on theX− side may be substantially the same as shown in FIG. 4D.Alternatively, in a bottom view, the width D1C in the X direction of thedepressed portion 16C located at the center of the base member, thewidth D1L in the X direction of the depressed portion 16L located on theX+ side, and/or the width D1R in the X direction of the depressedportion 16R located on the X− side may be different as shown in FIG. 4Eand FIG. 4F. In a bottom view, even in the case where the width D1C inthe X direction of the depressed portion 16C located at the center ofthe base member, the width D1L in the X direction of the depressedportion 16L located on the X+ side, and/or the width D1R in the Xdirection of the depressed portion 16R located on the X− side aredifferent, the depths in the Z direction of the depressed portions maybe the same of different. Also, in a bottom view, it is preferable thatthe width D1L in the X direction of the depressed portion 16L located onthe X+ side be substantially the same as the width D1R in the Xdirection of the depressed portion 16R located on the X− side. Thisstructure can alleviate a mass imbalance between the bonding memberformed inside the depressed portion 16L located on the X+ side and thebonding member formed inside the depressed portion 16R located on the X−side. Accordingly, the light-emitting device is less likely to beinclined after being mounted on the mounting board.

On the back surface, the depressed portions 16 are preferablybilaterally symmetric with respect to the center line of the base memberparallel to the second direction (i.e., Y direction). This structureachieves effective self-alignment when the light-emitting device ismounted on or above the mounting board with the bonding members, and thelight-emitting device can be precisely mounted within the mountingregion.

On the back surface, the opening of each of the depressed portionspreferably has a substantially semicircular shape. To form the depressedportion, a circular opening shape can be formed by drilling, and asubstantially semicircular shape on the back surface can be easilyformed by cutting part of the circular depressed portion by dicing orthe like. Also, forming the opening shape of the depressed portion onthe back surface into a substantial semicircle without corners canalleviate stress concentration in the depressed portion, and thus canalleviate fracturing of the base member.

The light-emitting device 1000 may include light-transmissive members 30as shown in FIG. 1A, FIG. 2A, and FIG. 2B. The light-transmissivemembers 30 are preferably positioned on the light-emitting elements 20.Positioning the light-transmissive members on the light-emittingelements protects the light-emitting elements 20 against externalstress. The covering member 40 preferably covers the lateral surfaces ofthe light-transmissive members 30. This structure can make light fromthe light-emitting device more similar to a point light source. Makingthe light-emitting device more similar to a point source facilitates,for example, adjustment of light distribution using an optical systemsuch as a lens.

The light-emitting elements 20 each have a mounting surface facing thesubstrate 10 and a light-extracting surface 201 opposite to the mountingsurface. In the case where the light-emitting elements are flip-chipmounted, the surfaces opposite to the surfaces on which positive andnegative electrodes of the light-emitting elements are located are usedas the light-extracting surfaces as shown in FIG. 2A. Thelight-transmissive members 30 may be bonded to the light-emittingelements 20 with light-guiding members 50 therebetween. Thelight-guiding members 50 may be disposed only between thelight-extracting surfaces 201 of the light-emitting elements and thelight-transmissive members 30 to bond the light-emitting elements 20 andthe covering member 40. Alternatively, the light-guiding members 50 maycover the region from the light-extracting surfaces 201 of thelight-emitting elements to the lateral surfaces 202 of thelight-emitting elements to bond the light-emitting elements 20 to thecovering member 40. The light-guiding members 50 have a highertransmittance of light from the light-emitting elements 20 than thetransmittance of the covering member 40. Hence, if the light-guidingmembers 50 cover the lateral surfaces 202 of the light-emittingelements, light emitted from the lateral surfaces of the light-emittingelements 20 can be easily extracted out of the light-emitting devicethrough the light-guiding members 50, thereby enhancing the lightextraction efficiency.

In the case where a plurality of light-emitting elements 20 areincluded, a peak wavelengths of one of the light-emitting elements andthe other one of the light-emitting elements may be the same ordifferent. In the case where the peak wavelengths of one of thelight-emitting elements and the other one of the light-emitting elementsare different, the light-emitting elements preferably include alight-emitting element having an emission peak wavelength in the rangeof 430 nm to less than 490 nm (i.e., wavelength range in the blueregion) and a light-emitting element having an emission peak wavelengthin the range of 490 nm to 570 nm (i.e., wavelength range in the greenregion). This structure can improve color rendering properties of thelight-emitting device.

The light-transmissive members 30 may contain a wavelength conversionsubstance 32 as shown in FIG. 2A and FIG. 2B. The wavelength conversionsubstance 32 is a member that absorbs at least part of primary lightfrom the light-emitting elements 20 and emits secondary light thatdiffers in wavelengths from the primary light. The light-transmissivemembers 30 containing the wavelength conversion substance 32 can realizeoutput of mixed light generated by combination of the primary lightemitted from the light-emitting elements 20 and the secondary lightemitted from the wavelength conversion substance 32. For example, ifblue LEDs are used as the light-emitting elements 20 and a phosphor suchas YAG is used as the wavelength conversion substance 32, alight-emitting device capable of outputting white light can be obtainedby mixing blue light from the blue LEDs and yellow light emitted fromthe phosphor excited by the blue light.

The wavelength conversion substance may be uniformly dispersed in thelight-transmissive members or may be contained more densely in a regionnear the light-emitting elements than in a region near the uppersurfaces of the light-transmissive members 30. This structure allows amatrix 31 of the light-transmissive members 30 to also function as aprotective layer, and thus can alleviate deterioration of the wavelengthconversion substance 32 even in the case where a wavelength conversionsubstance 32 that is vulnerable to water is used. Also, thelight-transmissive members 30 may each include a layer containing thewavelength conversion substance 32 and a layer 33 containingsubstantially no wavelength conversion substance as shown in FIG. 2A andFIG. 2B. If the light-transmissive member 30 includes the layer 33containing substantially no wavelength conversion substance on the layercontaining the wavelength conversion substance 32, the layer 33containing substantially no wavelength conversion substance alsofunctions as a protective layer, and thus can alleviate deterioration ofthe wavelength conversion substance 32. Examples of the wavelengthconversion substance 32 that is vulnerable to water includemanganese-activated fluoride phosphors. Manganese-activated fluoridephosphors are suitable in view of color reproducibility because emissionof light having a comparatively narrow spectral linewidth can beobtained.

As shown in FIG. 2B, the via holes 15 are disposed inside holespenetrating through the base member 11 from the front surface 111 to theback surface 112. In each of the via holes 15, a fourth wiring 151covering the surface of the through-hole in the base member and a fillermember 152 filled into the fourth wiring 151 may be provided. The fillermember 152 may be electrically-conductive or insulative. A resinmaterial is preferably used for the filler member 152. Uncured resinmaterials generally have higher fluidity than the fluidity of unhardenedmetal materials, and are easily filled into the fourth wiring 151.Hence, use of a resin material for the filler member facilitatesmanufacture of the substrate. Examples of the resin material that iseasily filled include epoxy resins. In the case where a resin materialis used as the filler member, an additive member is preferably containedin order to decrease the coefficient of linear expansion. The differencein the coefficients of linear expansion between the fourth wiring andthe filler member is thus reduced, thereby alleviating generation ofgaps between the fourth wiring and the filler member due to heatgenerated from the light-emitting elements. Examples of the additivemember include silicon oxide. In the case where a metal material is usedas the filler member 152, the heat dissipation can be improved.

As shown in FIG. 4A, the area of each via hole 15 on the back surface issmaller than the area of the opening of each depressed portion 16 on theback surface. Hence, although the via holes 15 penetrate through thebase member 11, the mechanical strength of the base member 11 is lesslikely to be reduced because via holes 15 are smaller in area than theopenings of the depressed portions 16 on the back surface.

It is preferable that one of the depressed portions 16 be locatedbetween one of the via holes 15 and an adjacent one of the via holes ina back view as shown in FIG. 4A. In other words, in a back view, thedepressed portion 16 is preferably located on the straight lineconnecting the via hole 15 and an the adjacent via hole 15. Thisstructure can enhance efficiency in transfer of heat generated from thelight-emitting elements to the via holes 15 and thereafter to the thirdwirings 14 located inside the depressed portions 16. The heattransferred to the third wirings 14 is transferred to the mounting boardvia the bonding members, and the heat dissipation of the light-emittingdevice is thus improved.

Also, it is preferable that one of the via holes 15 be located betweenone of the depressed portions 16 and an adjacent one of the depressedportions in a back view as shown in FIG. 4A. In other words, in a backview, the via hole 15 is preferably located on the straight lineconnecting the depressed portion 16 and the adjacent depressed portion16. This structure can enhance efficiency in transfer of heat generatedfrom the light-emitting elements to the via holes 15 and thereafter tothe third wirings 14 located inside the depressed portions. Thisstructure improves the heat dissipation of the light-emitting device.

As shown in FIG. 2B, the light-emitting elements 20 each include atleast a semiconductor layered body 23 provided with positive andnegative electrodes 21 and 22. Preferably, the positive and negativeelectrodes 21 and 22 are formed on the same surface of thelight-emitting element 20, and the light-emitting element 20 isflip-chip mounted on the substrate 10. This structure eliminates theneed for wires through which electricity is supplied to the positive andnegative electrodes of the light-emitting element, and thus can downsizethe light-emitting device. The light-emitting element 20 includes anelement substrate 24 in the present embodiment, but the elementsubstrate 24 may be removed. In the case where the light-emittingelement 20 is flip-chip mounted on the substrate 10, the positive andnegative electrodes 21 and 22 of the light-emitting element areconnected to the first wirings 12 via electrically-conductive adhesivemembers 60.

In the case where the light-emitting device 1000 includes a plurality oflight-emitting elements 20, the light-emitting elements are preferablyaligned in the first direction (i.e., X direction) as shown in FIG. 2B.This structure allows the width of the light-emitting device 1000 in thesecond direction (Y direction) to be smaller, thereby slimming down thelight-emitting device. The number of the light-emitting elements may bethree or more, or may be one.

As shown in FIG. 3C and FIG. 4A, the substrate 10 includes the basemember 11, the first wirings 12, and the second wirings 13. The basemember 11 has the front surface 111 extending in the first direction,which is the longitudinal direction, and the second direction, which isthe width direction; the back surface 112 opposite to the front surface;the bottom surface 113 adjacent and perpendicular to the front surface111; and the upper surface 114 opposite to the bottom surface 113.

The light-emitting device 1000 may include insulating films 18 coveringpart of the second wirings 13 as shown in FIG. 4A. Providing theinsulating films 18 can ensure insulation and prevent short circuits onthe back surface. This can also alleviate peeling of the second wiringsfrom the base member.

A lateral surface 403 of the covering member 40 along the longitudinaldirection located on the bottom surface 113 side is preferably inclinedtoward the inside of the light-emitting device 1000 in the Z directionas shown in FIG. 5A. This structure can alleviate contact of the lateralsurface 403 of the covering member 40 with the mounting board whenmounting the light-emitting device 1000 on or above the mounting board,thereby easily achieving a stable mounting orientation of thelight-emitting device 1000. Also, the structure can reduce the stressgenerated by contact of the covering member with the mounting board whenthe covering member 40 is expanded by heat. A lateral surface 404 of thecovering member 40 along the longitudinal direction located on the uppersurface 114 side is preferably inclined toward the inside of thelight-emitting device 1000 in the Z direction. This structure canalleviate contact of the lateral surface of the covering member 40 witha suction nozzle (also referred to as collet), thereby reducing damageto the covering member 40 at the time of suction of the light-emittingdevice 1000. Also, peripheral members are in contact with the uppersurface 114 of the base member 11 in advance of the lateral surface 404of the covering member 40 when the light-emitting device 1000 isincorporated into a lighting unit or the like, thereby reducing stresson the covering member 40. As described above, the lateral surface 403of the covering member 40 along the longitudinal direction located onthe bottom surface 113 side and the lateral surface 404 of the coveringmember 40 along the longitudinal direction located on the upper surface114 side are preferably inclined toward the inside of the light-emittingdevice 1000 in the direction (i.e., Z direction) from the back surfacetoward the front surface. An inclination angle θ of the covering member40 can be appropriately selected but is preferably in the range of 0.3°to 3°, more preferably 0.5° to 2°, even more preferably 0.7° to 1.5°, inview of ease of exerting such effects and the strength of the coveringmember 40.

The right and left lateral surfaces of the light-emitting device 1000preferably have substantially the same shape as shown in FIG. 5A andFIG. 5B. This structure enables miniaturization of the light-emittingdevice 1000.

It is preferable that a lateral surface 405 of the covering member 40along the width direction be substantially flush with a lateral surface105 of the substrate 10 along the width direction as shown in FIG. 6.This structure allows the length in the longitudinal direction (Xdirection) to be smaller, thereby miniaturizing the light-emittingdevice.

Second Embodiment

A light-emitting device 2000 according to a second embodiment of thepresent disclosure shown in FIG. 7 to FIG. 9B and the light-emittingdevice 1000 according to the first embodiment are different in thenumber of light-emitting elements mounted on the substrate and thenumbers of depressed portions and via holes included in the base member.The shape of the depressed portions 16 is the same as the shape in thefirst embodiment.

As shown in FIG. 8A, the depth of each depressed portion from the backsurface toward the front surface of the light-emitting device 2000 islarger on the bottom surface side than on the upper surface side as inthe first embodiment. Hence, the thickness of the base member on theupper surface side of the depressed portion can be larger than thethickness of the base member on the bottom surface side of the depressedportion. This structure can alleviate decrease in the mechanicalstrength of the base member. Also, the depressed portion having agreater depth on the bottom surface side can increase the volume of thebonding member formed inside the depressed portion, thereby improvingthe bonding strength between the light-emitting device 2000 and themounting board.

The number of the light-emitting element may be one as shown in FIG. 8B.If only one light-emitting element is mounted in the light-emittingdevice, the length in the first direction (i.e., X direction) can besmaller than in the case where a plurality of light-emitting elementsare mounted, thereby miniaturizing the light-emitting device. The numberof the depressed portions may also be changed as appropriate inaccordance with reduction in the length of the light-emitting device inthe first direction (i.e., X direction). For example, the number of thedepressed portions 16 may be two as shown in FIG. 9A. The number of thedepressed portions 16 may be one, or may be three or more.

It is preferable that a plurality of via holes 15 be located between oneof the depressed portions 16 and an adjacent one of the depressedportions 16 in a back view as shown in FIG. 9B. In other words, in aback view, a plurality of via holes 15 are preferably located on thestraight line connecting the one of the depressed portions 16 and theadjacent one of the depressed portions 16. This structure can enhanceefficiency in transfer of heat generated from the light-emittingelements to via holes 15 and thereafter to the third wirings 14 locatedinside the depressed portions. This structure can improve the heatdissipation performance of the light-emitting device.

Third Embodiment

A light-emitting device 3000 according to a third embodiment of thepresent disclosure shown in FIG. 10 to FIG. 14 and the light-emittingdevice 1000 according to the first embodiment are different in theshapes of the depressed portions 16.

The light-emitting device 3000 includes the substrate 10, one or morelight-emitting elements 20, and the covering member 40, like thelight-emitting device 1000. The substrate 10 includes the base member11, the first wirings 12, the second wirings 13, the third wirings 14,and the via holes 15. The base member 11 has the front surface 111extending in the first direction, which is the longitudinal direction,and the second direction, which is the width direction; the back surface112 opposite to the front surface; the bottom surface 113 adjacent andperpendicular to the front surface 111; the upper surface 114 oppositeto the bottom surface 113; and lateral surfaces 115 between the frontsurface 111 and the back surface 112. The base member 11 furtherincludes a plurality of depressed portions 16. The depressed portions 16include: a central depressed portion 161 that opens on the back surface112 and the bottom surface 113; and edge depressed portions 162 thatopen on the back surface 112, the bottom surface 113, and the lateralsurfaces 115. The third wirings 14 cover the inner walls of thedepressed portions 16 and are electrically connected to the secondwirings 13.

As shown in FIG. 14, the depths of the central depressed portion 161and/or the edge depressed portions 162 from the back surface toward thefront surface of the light-emitting device 3000 are larger on the bottomsurface side than on the upper surface side. Hence, the thickness of thebase member on the upper surface side of the central depressed portion161 and/or the edge depressed portions 162 can be larger than thethickness of the base member on the bottom surface side of the centraldepressed portion 161 and/or the edge depressed portions 162. Thisstructure can alleviate decrease in the mechanical strength of the basemember. Also, the central depressed portion 161 and/or the edgedepressed portions 162 having a greater depth on the bottom surface sidecan increase the volumes of the bonding members formed inside thecentral depressed portion 161 and/or the edge depressed portions 162,thereby improving the bonding strength between the light-emitting device3000 and the mounting board. The number of the central depressed portion161 and/or the edge depressed portion 162 is at least one.

As shown in FIG. 11 to FIG. 14, the edge depressed portions 162 openalso on the lateral surfaces 115 of the base member. This structureallows the bonding members to be located on the lateral surfaces 115sides of the base member, thereby further improving the bonding strengthbetween the light-emitting device 3000 and the mounting board. In thecase where the light-emitting device 3000 is mounted as a side-view typesuch that the bottom surface 113 of the base member 11 faces themounting board, having the edge depressed portions 162 is particularlypreferable. Having the edge depressed portions 162 can achieve fixationof the lateral surfaces 115 of the base member, thereby preventing oralleviate the Manhattan phenomenon, in which the light-emitting device3000 inclines on the mounting board, or in which the back surface of thebase member stands to face the mounting board. It is sufficient to haveat least one edge depressed portion 162, but having a plurality of edgedepressed portions 162 is preferable. Having a plurality of edgedepressed portions 162 can further improve the bonding strength betweenthe light-emitting device 3000 and the mounting board. In the case wherea plurality of edge depressed portions 162 are formed, the edgedepressed portions are preferably located on both ends of the basemember in the longitudinal direction (i.e., X direction) in a back view.This structure can further prevent or alleviate the Manhattanphenomenon.

In a back view, in the case where the shape of the central depressedportion 161 is a substantial semicircle, which is half of a circle, andin the case where the shape of the edge depressed portions 162 is asubstantial quarter of a circle, the diameters of the circles of thecentral depressed portion 161 and the edge depressed portions 162 may bedifferent or substantially the same. It is preferable that the diametersof the circles of the central depressed portion 161 and the edgedepressed portions 162 be substantially the same because the centraldepressed portion 161 and the edge depressed portions 162 can be formedwith one drill. Also, for example, the central depressed portion 161 andthe edge depressed portions 162 include inclined portions inclined fromthe bottom surface 113 as the thickness of the base member 11 becomeslarger in a sectional view in Z direction, the angles of the inclinedportion of the central depressed portion 161 and the inclined portionsof the edge depressed portions 162 may be different or substantially thesame. It is preferable that the angles of the inclined portion of thecentral depressed portion 161 and the inclined portions of the edgedepressed portions 162 be substantially the same because the centraldepressed portion 161 and the edge depressed portions 162 can be formedwith one drill.

As shown in FIG. 15 and FIG. 16, one light-transmissive member 30 may bedisposed on a plurality of light-emitting elements. This structure canincrease the area of the light-transmissive member in a front view,thereby improving the light extraction efficiency of the light-emittingdevice. Also, having only one emitting surface on the light-emittingdevice can alleviate the luminance non-uniformity of the light-emittingdevice.

In the case where one light-transmissive member 30 is located on aplurality of light-emitting elements, the light-guiding members 50bonding the light-emitting elements 20 to the light-transmissive member30 may be connected to or separated from each other. A light-guidingmember preferably fills the gap between one of the light-emittingelements and the other one of the light-emitting elements as shown inFIG. 16. This structure enables the light-guiding member to guide lightemitted from the light-emitting elements in a gap between the one of thelight-emitting elements and the other one of the light-emitting elementsto the light-transmissive member, and thus can reduce the luminancenon-uniformity of the light-emitting device. This structure can alsonarrow a portion of the covering member located between the one of thelight-emitting elements and the other one of the light-emitting elementsthereby alleviating deterioration of the covering member due to lightfrom the light-emitting elements. A material of the light-guiding memberis preferably one that is less likely deteriorated by light from thelight-emitting elements than the material for the covering member.

Fourth Embodiment

A light-emitting device 4000 according to a fourth embodiment of thepresent disclosure shown in FIG. 17 to FIG. 21 and the light-emittingdevice 2000 according to the second embodiment are different in theshapes of the depressed portions 16.

As shown in FIG. 21, the light-emitting device 4000 includes the edgedepressed portions 162. The edge depressed portions from the backsurface toward the front surface has the depth larger on the bottomsurface side than on the upper surface side. Hence, the thickness of thebase member on the upper surface side of the edge depressed portions canbe larger than the thickness of the base member on the bottom surfaceside of the depressed portions. This structure can alleviate decrease inthe strength of the base member. Also, the edge depressed portionshaving the greater depth on the bottom surface side can increase thevolumes of the bonding members formed inside the edge depressedportions, thereby improving the bonding strength between thelight-emitting device 4000 and the mounting board.

As shown in FIG. 18 to FIG. 21, the edge depressed portions 162 openalso to the lateral surfaces 115 of the base member. This structureallows the bonding members to be located on the lateral surfaces 115sides of the base member, thereby further improving the bonding strengthbetween the light-emitting device 4000 and the mounting board.

Fifth Embodiment

A light-emitting device 5000 according to a fifth embodiment of thepresent disclosure shown in FIG. 22 and the light-emitting device 4000according to the fourth embodiment are different in that the centraldepressed portion 161 is formed.

The light-emitting device 5000 has the central depressed portion 161 andthe edge depressed portions 162, thereby increasing portions to bebonded with the bonding members, resulting in improvement of the bondingstrength between the light-emitting device and the mounting board. Thecentral depressed portion 161 and/or the edge depressed portions 162from the back surface toward the front surface have depths larger on thebottom surface side than on the upper surface side. This structure canimprove the bonding strength between the light-emitting device 5000 andthe mounting board.

Sixth Embodiment

A light-emitting device 6000 according to a sixth embodiment of thepresent disclosure shown in FIG. 23 and the light-emitting device 1000according to the first embodiment are different in the shapes of thesecond wirings and the insulating film and in that the depressed portionat the center of the light-emitting device (i.e., central depressedportion) is not formed.

In a back view, second wirings 13 of the light-emitting device 6000 arelocated between two edge depressed portions, and includes an exposedportion 131 exposed from the insulating film 18. The exposed portion 131on the back surface is surrounded by the insulating film 18 except forthe bottom surface 113 side. Disposing a bonding member on the exposedportion 131 can improve the bonding strength between the light-emittingdevice and the mounting board. The shape of the exposed portion 131 in aback view may be appropriately selected, for example, it can bequadrilaterals and hemispheres. The shape of the exposed portion 131 ina back view can be easily changed by changing the shape of theinsulating film. The shape of the exposed portion 131 in a back viewpreferably includes a narrow portion 132 on the bottom surface side anda wide portion 133 positioned at an area extending in the seconddirection (i.e., Y direction). Providing the narrow portion canalleviate intrusion of a flux or the like contained in the bondingmember into the gap below the light-emitting element along the surfaceof the exposed portion 131 when the light-emitting device is mounted.Also, the shape of the second wiring 13 exposed from the insulating film18 is preferably bilaterally symmetric with respect to the center lineof the base member parallel to the second direction (i.e., Y direction).This structure can achieve effective self-alignment when thelight-emitting device is mounted on or above the mounting board with thebonding members, and the light-emitting device can be precisely mountedwithin the mounting region.

Seventh Embodiment

A light-emitting device 7000 according to a seventh embodiment of thepresent disclosure shown in FIG. 24 and the light-emitting device 4000according to the fourth embodiment are different in the shapes of thesecond wirings and the insulating film.

Like the light-emitting device 6000, in a back view, second wirings 13of the light-emitting device 7000 are located between two edge depressedportions and includes the exposed portion 131 exposed from theinsulating film 18. The exposed portion 131 on the back surface issurrounded by the insulating film 18 except for the bottom surface 113side. Disposing a bonding member on the exposed portion 131 can improvethe bonding strength between the light-emitting device 7000 and themounting board.

The shape of lands 70 on the mounting board on which the light-emittingdevice is to be mounted is not particularly limited, and the shape maybe a substantial quadrilateral or a substantial circle. For example,each land 70 on the mounting board on which the light-emitting deviceaccording to the first embodiment is to be mounted may include a wideportion W10 widened in the X direction and a narrow portion W9 narrowedin the X direction as shown in FIG. 25A. Positioning the narrow portionW9 so as to overlap the depressed portion in a bottom view facilitatesself-alignment when the light-emitting device is mounted on or above themounting board. Also, including the wide portion W10 in the land 70 canincrease the area of the land 70 in a bottom view. This structure canalleviate unevenness in the thickness of the bonding members. Forexample, the depressed portion of the light-emitting device according tothe first embodiment has the greatest depth at the center in the Zdirection. When such the light-emitting device is mounted on themounting board, the mounting board preferably include a land in which alength W12 at the center in the Z direction is larger than a length W11at an end in the Z direction as shown in FIG. 25B. This structure canfacilitate self-alignment when the light-emitting device is mounted onor above the mounting board. Also, the land 70 including the wideportion W10 and the narrow portion W9 may have a length W14 at thecenter of the narrow portion of the land 70 in the Z direction largerthan a length W13 at an end of the narrow portion of the land 70 in theZ direction as shown in FIG. 25C. This structure can facilitateself-alignment when the light-emitting device according to the firstembodiment is mounted on or above the mounting board, and can alleviateunevenness in the thickness of the bonding members.

For example, the depressed portion of the light-emitting deviceaccording to the fourth embodiment has the depth becoming larger in theZ direction as the distance from the center of the light-emitting deviceincreases. When such the light-emitting device is mounted on themounting board, as shown in FIG. 26A, the mounting board preferablyinclude a land in which a length W15 in the Z direction on the side farfrom the center in X direction of the light-emitting device is largerthan a length W16 in the Z direction on the side near the center of thelight-emitting device. This structure can facilitate self-alignment whenthe light-emitting device is mounted on or above the mounting board.Also, as shown in FIG. 26B, the land 70 including the wide portion W10widened in the X direction and the narrow portion W9 narrowed in the Xdirection. The land 70 preferably has lengths W17 and W18 of the narrowportion of the land 70 in the Z direction. The length W18 denotes theside at the end far from the center of the light-emitting device. Thelength W18 denotes the side at the end near the center of thelight-emitting device. The length W17 is longer then the length W18.Positioning the narrow portion so as to overlap the edge depressedportion in a bottom view can facilitate self-alignment when thelight-emitting device is mounted on or above the mounting board. Also,the land 70 includes the wide portion, thereby increasing the area ofthe land 70 in a bottom view. This structure can alleviate unevenness inthe thickness of the bonding members. Making the length W17 larger thanthe length W18 can facilitate self-alignment when the light-emittingdevice is mounted on or above the mounting board.

Eighth Embodiment

A light-emitting device 8000 according to an eighth embodiment of thepresent disclosure shown in FIG. 27 to FIG. 30 and the light-emittingdevice 1000 according to the first embodiment are different in thenumber of light-emitting elements mounted on the substrate, the numbersof depressed portions and via holes of the base member, and the shape ofthe light-transmissive member. The shape of the depressed portions 16 isthe same as the shape in the first embodiment.

As shown in FIG. 28A, the depressed portions from the back surfacetoward the front surface of the light-emitting device 8000 each have adepth greater on the bottom surface side than on the upper surface sideas in the first embodiment. Hence, the thickness of the base member onthe upper surface side of the depressed portions can be greater than thethickness of the base member on the bottom surface side of the depressedportions. This structure can alleviate decrease in the strength of thebase member. Also, making the depressed portions deeper on the bottomsurface side can increase volumes of the bonding members formed insidethe depressed portions, thereby improving the bonding strength betweenthe light-emitting device 8000 and the mounting board.

The number of the light-emitting elements may be three as shown in FIG.28B. The peak wavelengths of the three light-emitting elements may bethe same as or different to one another. It is also possible that thepeak wavelengths of two light-emitting elements are the same and thepeak wavelength of the other one light-emitting element differs from thepeak wavelengths of the two light-emitting elements. The statement that“the peak wavelengths of light-emitting elements are the same” in thepresent specification means that a tolerance of about 5 nm isacceptable. In the case where the peak wavelengths of the light-emittingelements are different, the light-emitting elements preferably includefirst light-emitting elements 20B having an emission peak wavelength inthe range of from 430 nm to less than 490 nm (i.e., wavelength range inthe blue region) and a second light-emitting element 20G having anemission peak wavelength in the range of from 490 nm to 570 nm (i.e.,wavelength range in the green region) as shown in FIG. 28B. Inparticular, a light-emitting element having a half-width of 40 nm orless is preferably used as the second light-emitting element 20G, and alight-emitting element having a half-width of 30 nm or less is morepreferably used. Using such a light-emitting device can achieve greenlight having a sharp peak more easily than in the case where green lightis obtained using a green phosphor. Accordingly, a liquid-crystaldisplay including the light-emitting device 8000 can achieve high colorreproducibility.

The arrangement of the first light-emitting elements 20B and the secondlight-emitting element 20G is not particularly limited. Preferably, oneof the first light-emitting elements 20B that is a blue light-emittingelement, the second light-emitting element 20G that is a greenlight-emitting element, and the other first light-emitting element 20Bthat is a blue light-emitting element, are aligned in order from theleft side as shown in FIG. 28B. Alternately disposing the firstlight-emitting elements 20B and the second light-emitting element 20G ina line improves color mixing properties of the light-emitting device. Asecond light-emitting element, a first light-emitting element, and asecond light-emitting element may be aligned in order from the leftside. Depending on the desired light emission characteristics, thenumber of the first light-emitting elements 20B may be larger than thenumber of the second light-emitting elements 20G, the number of thesecond light-emitting elements 20G may be larger than the number of thefirst light-emitting elements 20B, or the number of the firstlight-emitting elements 20B may be the same as the number of the secondlight-emitting elements 20G. A light-emitting device having an desiredcolor and light quantity can be provided by adjusting the number oflight-emitting elements.

In the case where one light-transmissive member 30 is provided on theplurality of first light-emitting elements 20B and the secondlight-emitting element 20G as shown in FIG. 28B, it is preferable thatthe wavelength conversion substance 32 hardly absorb green light fromthe second light-emitting element 20G and emit red light. That is, it ispreferable that the wavelength conversion substance 32 does notsubstantially convert green light into red light. The reflectance of thewavelength conversion substance 32 with respect to green light ispreferably 70% or more on average in the wavelength range of greenlight. Designing the light-emitting device is facilitated by employing aphosphor having a high reflectance with respect to green light, that is,less likely to absorb green light, that is, less likely to convert thewavelength of green light, as the wavelength conversion substance 32.

In the case where a red phosphor readily absorbs green light is used,the output balance of the light-emitting device is required to bedetermined in consideration of wavelength conversion by the wavelengthconversion substance 32 not only for the first light-emitting elements20B but also for the second light-emitting element 20G. On the otherhand, in the case where the wavelength conversion substance 32 thathardly converts the wavelength of green light is used, the outputbalance of the light-emitting device can be designed in consideration ofonly wavelength conversion of blue light emitted from the firstlight-emitting elements 20B.

Examples of the wavelength conversion substance 32 having suchpreferable properties include red phosphors below. The wavelengthconversion substance 32 is at least one of the followings.

A first type is red phosphors having compositions represented by thefollowing general formula (I).

A₂MF₆:Mn⁴⁺  (I)

In the above general formula (I), A is at least one selected from thegroup consisting of K, Li, Na, Rb, Cs, and NH⁴⁺, and M is at least oneelement selected from the group consisting of the group IV elements andthe group XIV elements.

The group IV elements include titanium (Ti), zirconium (Zr), and hafnium(Hf). The group XIV elements include silicon (Si), germanium (Ge), tin(Sn), and lead (Pb).

Specific examples of the first-type red phosphors include K₂SiF₆:Mn⁴⁺,K₂(Si,Ge)F₆:Mn⁴⁺, and K₂TiF₆:Mn⁴⁺.

A second type is red phosphors having compositions represented by3.5MgO.0.5MgF₂·GeO₂:Mn⁴⁺ or red phosphors having compositionsrepresented by the following general formula (II).

(x−a)MgO.a(Ma)O.b/2(Mb)₂O₃ .yMgF₂ .c(Mc)X₂.(1−d−e)GeO₂ .d(Md)O₂.e(Me)₂O₃:Mn⁴⁺   (II)

In the above general formula (II): Ma is at least one selected from Ca,Sr, Ba, and Zn; Mb is at least one selected from Sc, La, and Lu; Mc isat least one selected from Ca, Sr, Ba, and Zn; X is at least oneselected from F and Cl; Md is at least one selected from Ti, Sn, and Zr;and Me is at least one selected from B, Al, Ga, and In. Also, x, y, a,b, c, d, and e satisfy 2≤x≤4, 0<y≤2, 0≤a≤1.5, 0≤b<1, 0≤c≤2, 0≤d≤0.5, and0≤e<1.

The light-emitting device 8000 includes three light-emitting elements,therefore, its length in the first direction (i.e., X direction) tendsto be larger than in the case where one light-emitting element isincluded. Hence, the numbers of the depressed portions and the via holesmay be changed as appropriate. For example, four depressed portions 16and four via holes may be formed as shown in FIG. 30.

One light-transmissive member 30 may be disposed on each of the firstlight-emitting elements and the second light-emitting element as shownin FIG. 31, or one light-transmissive member 30 may be disposed on aplurality of light-emitting elements as shown in FIG. 28B. In the casewhere one light-transmissive member 30 is located on each of the firstlight-emitting elements and the second light-emitting element as shownin FIG. 31, the wavelength conversion substance 32 contained in thelight-transmissive members 30 disposed on the first light-emittingelements 20B may be the same as or different to the wavelengthconversion substance 32 the light-transmissive member 30 on the secondlight-emitting element 20G. For example, in the case where thewavelength conversion substance 32 hardly absorbs green light from thesecond light-emitting element 20G and hardly emit red light, thelight-transmissive members 30 on the first light-emitting elements 20Bmay contain a red phosphor as the wavelength conversion substance 32,and the light-transmissive member 30 on the second light-emittingelement 20G may not contain a red phosphor as the wavelength conversionsubstance 32. With this structure, the output balance of thelight-emitting device can be designed in consideration of onlywavelength conversion of blue light emitted from the firstlight-emitting elements 20B. In the case where one light-transmissivemember 30 is located on each of the first light-emitting elements andthe second light-emitting element, the covering member is formed betweenrespective of the light-transmissive members 30 on the firstlight-emitting elements 20B and the light-transmissive member 30 on thesecond light-emitting element 20G. In the case where onelight-transmissive member 30 is disposed on a plurality oflight-emitting elements as shown in FIG. 28B, the area of thelight-transmissive member 30 in a front view can be increased, therebyimproving the light extraction efficiency of the light-emitting device.Also, having only one light emitting surface in the light-emittingdevice can reduce the luminance non-uniformity of the light-emittingdevice.

In the case where one light-transmissive member 30 is disposed on aplurality of light-emitting elements, the light-guiding members 50bonding the light-emitting elements 20 to the light-transmissive member30 may be connected to or separated from each other in the regionsbetween respective of the first and second light-emitting elements 20Band 20G. The light-guiding member 50 preferably fills the gap betweenone light-emitting element and another light-emitting element as shownin FIG. 28B. This structure enables the light-guiding member to guidelight emitted from the light-emitting elements in a gap between onelight-emitting element and another light-emitting element to thelight-transmissive member, and thus reduces the luminance non-uniformityof the light-emitting device.

The light-transmissive member 30 may include a layer containing thewavelength conversion substance 32 and a layer 33 containingsubstantially no wavelength conversion substance as shown in FIG. 28Band FIG. 31. If the light-transmissive member 30 includes the layer 33containing substantially no wavelength conversion substance on the layercontaining the wavelength conversion substance 32, the layer 33containing substantially no wavelength conversion substance alsofunctions as a protective layer, and thus can alleviate deterioration ofthe wavelength conversion substance 32. In the case where onelight-transmissive member 30 is located on each of the firstlight-emitting elements and the second light-emitting element as shownin FIG. 31, the thicknesses of the layers 33 containing substantially nowavelength conversion substance located on the first light-emittingelements 20B and the layer 33 containing substantially no wavelengthconversion substance located on the second light-emitting element 20Gmay be the same or different. Also, in the case where onelight-transmissive member 30 is located on each of the firstlight-emitting elements and the second light-emitting element, thethicknesses of the layers containing the wavelength conversion substance32 located on the first light-emitting elements 20B and the layercontaining the wavelength conversion substance 32 located on the secondlight-emitting element 20G may be the same or different. The statementthat “the thicknesses are the same” in the present specification meansthat a tolerance of about 5 μm is acceptable.

The following describes the components of a light-emitting deviceaccording to one embodiment of the present disclosure.

Substrate 10

The substrate 10 is a member on which the light-emitting element ismounted. The substrate 10 includes at least the base member 11, thefirst wirings 12, the second wirings 13, the third wirings 14, and thevia holes 15.

Base Member 11

The base member 11 can include an insulating member such as resins orfiber-reinforced resins, ceramics, and glass. Examples of the resins orfiber-reinforced resins include epoxy resins, glass epoxy resins,bismaleimide-triazine (BT) resins, and polyimides. Examples of theceramics include aluminum oxide, aluminum nitride, zirconium oxide,zirconium nitride, titanium oxide, titanium nitride, and mixturesthereof. Among these base members, a base member having the coefficientof linear expansion close to that of the light-emitting element isparticularly preferably used. The lower limit of the thickness of thebase member can be appropriately selected. The lower limit is preferably0.05 mm or more, more preferably 0.2 mm or more, in view of the strengthof the base member. The upper limit of the thickness of the base memberis preferably 0.5 mm or less, more preferably 0.4 mm or less, in view ofthe thickness/depth of the light-emitting device.

First Wirings 12, Second Wirings 13, and Third Wirings 14

The first wirings are disposed on the front surface of the substrate andelectrically connected to the light-emitting element. The second wiringsare disposed on the back surface of the substrate and electricallyconnected to the first wirings through the via holes. The third wiringscover the inner walls of the depressed portions and are electricallyconnected to the second wirings. The first wirings, second wirings, andthird wirings can be formed of copper, iron, nickel, tungsten, chromium,aluminum, silver, gold, titanium, palladium, rhodium, or an alloy ofthese metals. A single layer or multiple layers mainly containing thesemetals or alloys of these metals may be used. In particular, copper or acopper alloy is preferable in view of heat dissipation. Surface layersof the first wirings and/or the second wirings may mainly containmaterials such as silver, platinum, aluminum, rhodium, gold, and alloysof these metals in view of wettability and/or light reflectivity and thelike of the electrically-conductive adhesive members.

Via Holes 15

The via holes 15 are formed inside the holes penetrating through thebase member 11 from the front surface to the back surface and aremembers that electrically connect the first wirings and the secondwirings. The via holes 15 each include the fourth wiring 151 coveringthe surface of the through-hole in the base member and the filler member152 filled into the fourth wiring 151. The fourth wiring 151 can beformed of such an electrically-conductive member as used for the firstwirings, the second wirings, and the third wirings. The filler member152 can be formed of an electrically-conductive member or an insulatingmember.

Insulating Film 18

The insulating film 18 is a member intended to ensure insulation andprevent short circuits on the back surface. The insulating film may beformed of a material used in the field of the disclosure. Examples ofthe material include thermosetting resins and thermoplastic resins.

Light-Emitting Element 20

The light-emitting element 20 is a semiconductor element that emitslight by itself when voltage is applied, and a known semiconductorelement made of a nitride semiconductor or the like can be used.Examples of the light-emitting element 20 include LED chips. Thelight-emitting element 20 includes at least the semiconductor layeredbody 23 and, in many cases, the element substrate 24. The shape in a topview of the light-emitting element is preferably a rectangle, inparticular a square or a rectangle elongated in one direction, but othershapes may be employed. For example, a hexagon can increase thelight-emission efficiency. The lateral surfaces of the light-emittingelement may be perpendicular to the upper surface, or may be inclinedinward or outward. The light-emitting element includes positive andnegative electrodes. The positive and negative electrodes can be formedof a material mainly containing gold, silver, tin, platinum, rhodium,titanium, aluminum, tungsten, palladium, nickel, or an alloy thereof.The emission peak wavelength of the light-emitting element can beselected from the ultraviolet range to the infrared range by changingthe semiconductor materials or their mixing ratios of the crystals. Anitride semiconductor, which can emit short-wavelength light capable ofefficiently exciting the wavelength conversion substance, is preferablyused as the semiconductor material. The nitride semiconductor istypically represented by the general formula In_(x)Al_(y)Ga_(1-x-y)N(0≤x, 0≤y, x+y≤1). The emission peak wavelength of the light-emittingelement is preferably in the range of 400 nm to 530 nm, more preferably420 nm to 490 nm, and even more preferably 450 nm to 475 nm in view oflight-emission efficiency, excitation of the wavelength conversionsubstance, color mixing relations with light emission of the wavelengthconversion substance, and such other conditions. In addition, InAlGaAssemiconductors, InAlGaP semiconductors, zinc sulfide, zinc selenide,silicon carbide, and the like can also be used. The element substrate ofthe light-emitting element is typically a crystal growth substrate onwhich a semiconductor crystal constituting the semiconductor layeredbody can be grown, but a support substrate may be employed to be bondedto the semiconductor element structure that is separated from thecrystal growth substrate. A light-transmissive element substrate canfacilitate employment of flip-chip mounting and enhancement of lightextraction efficiency. Examples of the matrix of the element substrateinclude sapphire, gallium nitride, aluminum nitride, silicon, siliconcarbide, gallium arsenide, gallium phosphide, indium phosphide, zincsulfide, zinc oxide, zinc selenide, and diamond. Among these materials,sapphire is preferable. The thickness of the element substrate can beappropriately selected and is, for example, in the range of 0.02 to 1mm, preferably 0.05 to 0.3 mm in view of the mechanical strength of theelement substrate and/or the thickness of the light-emitting device.

Light-Transmissive Member 30

The light-transmissive member is disposed on the light-emitting elementand protects the light-emitting element. The light-transmissive memberincludes at least the matrix below. The light-transmissive member canfunction as a wavelength conversion member by mixing the wavelengthconversion substance 32 in the matrix. The matrix of each layer has aconstitution described below also in the case where thelight-transmissive member includes the layer containing the wavelengthconversion substance and the layer containing substantially nowavelength conversion substance. The matrices of the layers may be thesame or different. It is not necessary that the light-transmissivemember contain the wavelength conversion substance. Thelight-transmissive member can employ a sintered body of the wavelengthconversion substance and an inorganic material such as alumina, aplate-shaped crystal of the wavelength conversion substance, or thelike.

Matrix 31 of Light-Transmissive Member

The matrix 31 of the light-transmissive member is not limited as long asthe matrix is light-transmissive with respect to light emitted from thelight-emitting element. The term “light-transmissive” means that thelight transmittance at the emission peak wavelength of thelight-emitting element is preferably 60% or more, more preferably 70% ormore, even more preferably 80% or more. The matrix of thelight-transmissive member can employ a silicone resin, an epoxy resin, aphenolic resin, a polycarbonate resin, an acrylic resin, a modifiedresin thereof, or glass. Among these materials, silicone resins andmodified silicone resins are preferable due to their good heat and lightresistance. Specific examples of the silicone resins include dimethylsilicone resins, phenyl-methyl silicone resins, and diphenyl siliconeresins. The light-transmissive member can include one of these matrixmaterials, or include two or more of these matrix materials layered oneach other. The “modified resins” in the present specification includehybrid resins.

Various fillers may be mixed in any of the above resins or glass for thematrix of the light-transmissive member. Examples of the fillers includesilicon oxide, aluminum oxide, zirconium oxide, and zinc oxide. Thesefillers can be used singly, or two or more of the fillers can be used incombination. Silicon oxide is particularly preferable due to the factthat silicone oxide have a small coefficient of thermal expansion. Usingnanoparticles as the filler can increase scattering of light emittedfrom the light-emitting element and reduces the quantity of thewavelength conversion substance to be used. The nanoparticles areparticles having diameters in the range of 1 nm to 100 nm. The “particlediameter” in the present specification is defined as, for example, D₅₀.

Wavelength Conversion Substance 32

The wavelength conversion substance absorbs at least part of the primarylight emitted from the light-emitting element and emits the secondarylight that differs in wavelengths from the primary light. Specificexamples of the wavelength conversion substance can be used singly, ortwo or more of the substances may be used in combination as describedbelow.

Examples of wavelength conversion substances that emit green lightinclude yttrium-aluminum-garnet phosphors (for example,Y₃(Al,Ga)₅O₁₂:Ce), lutetium-aluminum-garnet phosphors (for example,Lu₃(Al,Ga)₅O₁₂:Ce), terbium-aluminum-garnet phosphors (for example,Tb₃(Al,Ga)₅O₁₂:Ce) phosphors, silicate phosphors (for example,(Ba,Sr)₂SiO₄:Eu), chlorosilicate phosphors (for example,Ca₈Mg(SiO₄)₄Cl₂:Eu), β-SiAlON phosphors (for example,Si_(6-z)Al_(z)O_(z)N₈-z:Eu (0<z<4.2)), and SGS phosphors (for example,SrGa₂S₄:Eu). Examples of wavelength conversion substances that emityellow light include α-SiAlON phosphors (for example,M_(z)(Si,Al)₁₂(O,N)₁₆ (where 0<z≤2, and M is Li, Mg, Ca, Y, or alanthanoid element other than La or Ce)). Some of the above wavelengthconversion substances that emit green light emit yellow light. Also, forexample, yellow light can be obtained by substituting part of Y (i.e.,yttrium) in an yttrium-aluminum-garnet phosphor with Gd (i.e.,gadolinium) to shift its emission peak wavelength to a longerwavelength. Such wavelength conversion substances also includewavelength conversion substances that can emit orange light. Examples ofwavelength conversion substances that emit red light includenitrogen-containing calcium aluminosilicate (CASN or SCASN) phosphors(for example, (Sr,Ca)AlSiN₃:Eu). The examples also includemanganese-activated fluoride phosphors (phosphors represented by thegeneral formula (I) A₂[M_(1-a)Mn_(a)F₆] (in the general formula (I), Ais at least one selected from the group consisting of K, Li, Na, Rb, Cs,and NH₄, M is at least one element selected from the group consisting ofthe group IV elements and the group XIV elements, and a satisfies0<a<0.2)). Typical examples of the manganese-activated fluoridephosphors include manganese-activated potassium fluorosilicate phosphors(for example, K₂SiF₆:Mn).

Covering Member 40

The light reflectance of the covering member having light reflectivityat the emission peak wavelength of the light-emitting element ispreferably 70% or more, more preferably 80% or more, even morepreferably 90% or more, in view of upward light extraction efficiency.In addition, the covering member is preferably white. Thus, the coveringmember preferably contains a white pigment in the matrix. The coveringmember is in a liquid state before being hardened. The covering membercan be formed by transfer molding, injection molding, compressionmolding, potting, or the like.

Matrix of Covering Member

The matrix of the covering member can be a resin such as siliconeresins, epoxy resins, phenolic resins, polycarbonate resins, acrylicresins, and modified resins thereof. Among these materials, siliconeresins and modified silicone resins are preferable due to their goodheat and light resistance. Specific examples of the silicone resinsinclude dimethyl silicone resins, phenyl-methyl silicone resins, anddiphenyl silicone resins. The matrix of the covering member may containa filler similar to the foregoing filler in the light-transmissivemember.

White Pigment

As the white pigment, one of titanium oxide, zinc oxide, magnesiumoxide, magnesium carbonate, magnesium hydroxide, calcium carbonate,calcium hydroxide, calcium silicate, magnesium silicate, bariumtitanate, barium sulfate, aluminum hydroxide, aluminum oxide, zirconiumoxide, and silicon oxide can be used singly, or two or more of thesepigments can be used in combination. The shape of the white pigmentparticles can be appropriately selected, and may be irregular orcrushed, but is preferably spherical in view of fluidity. The particlediameter of the white pigment is, for example, in the range of about 0.1μm to 0.5 μm. The particles preferably have smaller diameters to enhanceeffects of light reflection and covering. The content of the whitepigment in the covering member having light reflectivity can beappropriately selected. In view of light reflectivity, the viscosity ina fluid state, and the like, the content is preferably in the range of,for example, 10 wt % to 80 wt %, more preferably 20 wt % to 70 wt %,even more preferably 30 wt % to 60 wt %. The term “wt %” meanspercentage by weight, that is, the proportion of the weight of amaterial of interest to the total weight of the covering member.

Light-Guiding Member 50

The light-guiding member bonds the light-emitting element to thelight-transmissive member and guides light from the light-emittingelement to the light-transmissive member. Examples of the matrix of thelight-guiding member include silicone resins, epoxy resins, phenolicresins, polycarbonate resins, acrylic resins, and modified resinsthereof. Among these materials, silicone resins and modified siliconeresins are preferable due to their good heat and light resistance andSpecific examples of the silicone resins include dimethyl siliconeresins, phenyl-methyl silicone resins, and diphenyl silicone resins. Thematrix of the light-guiding member may contain a filler similar to theforegoing filler in the light-transmissive member. The light-guidingmember may be omitted.

Electrically-Conductive Adhesive Members 60

The electrically-conductive adhesive members electrically connect theelectrodes of the light-emitting element and the first wirings. Theelectrically-conductive adhesive members can employ any one of: bumpsmainly containing gold, silver, copper, or the like; a metal pastecontaining a resin binder and powder of a metal such as silver, gold,copper, platinum, aluminum, and palladium; a tin-bismuth, tin-copper,tin-silver, or gold-tin solder or the like; and a brazing filler metalsuch as a low-melting-point metal.

A light-emitting device according to an embodiment of the presentdisclosure can be used for backlight devices for liquid-crystaldisplays, various lighting apparatuses, large displays, various displaysfor advertisements and destination guide, and projectors, as well as forimage scanners for apparatuses such as digital video cameras, facsimilemachines, copying machines, and scanners.

What is claimed is:
 1. A light-emitting device, comprising: a coveringmember; a first Light-emitting element arranged in the covering member,a second Light-emitting element arranged in the covering member to bespaced apart from the first Light-emitting element in a first direction;two light-transmissive members, each light-transmissive membercorresponding to an upper surface of each Light-emitting element andemitting light from each Light-emitting element therethrough; firstelectrodes formed on a lower surface of the first Light-emittingelement; and second electrodes formed on a lower surface of the secondLight-emitting element; and a substrate, wherein the substratecomprises: at least three depressed portions at a lower surface thereof,wherein a first depressed portion corresponds to the firstLight-emitting element, a second depressed portion corresponds to thesecond Light-emitting element, and a third depressed portion is arrangedbetween the first depressed portion and the second depressed portion inthe first direction; three or more pads each having a second wiring anda third wiring, each pad corresponding to each depressed portion andcovering at least a portion of each depressed portion; a first pair ofvia holes arranged to connect the first electrodes to one or more of thepads in a second direction perpendicular to the first direction; and asecond pair of via holes arranged to connect the second electrodes toone or more of the pads in the second direction; and wherein the thirddepressed portion is formed at a position between one of the first pairof via holes and one of the second pair of via holes.
 2. Thelight-emitting device according to claim 1, wherein the first pair ofvia holes face each other over the first depressed portion.
 3. Thelight-emitting device according to claim 2, wherein the second pair ofvia holes face each other over the second depressed portion.
 4. Thelight-emitting device according to claim 1, wherein the one of the firstpair of via holes is connected to one of the pads and the other of thefirst pair of via holes is connected to a different pad of the pads. 5.The light-emitting device according to claim 1, wherein a distancebetween two facing ends of the two light-transmissive members is smallerthan a distance between the one of the first pair of via holes and theone of the second pair of via holes, the one of the first pair of viaholes facing the one of the second pair of via holes over the thirddepressed portion.
 6. The light-emitting device according to claim 1,wherein a distance from one end of each light-transmissive member to oneof sidewalls of the covering member is smaller than a distance from theone of the second pair of via holes to one of sidewalls of thesubstrate.
 7. The light-emitting device according to claim 6, whereinthe one end of each light-transmissive member is proximate to the one ofthe sidewalls of the covering member, and one end of the second pair ofvia holes is proximate to the one of the sidewalls of the substrate. 8.The light-emitting device according to claim 1, further comprising: aninsulating film arranged between two adjacent pads.
 9. A light-emittingdevice, comprising: a first Light-emitting element structure,comprising: a first Light-emitting element; a first light-transmissivemember including a wavelength conversion substance and arranged on anupper surface of the first Light-emitting element; and a first pair ofelectrodes arranged on a lower surface of the first Light-emittingelement; a second Light-emitting element structure, comprising: a secondLight-emitting element; a second light-transmissive member including awavelength conversion substance and arranged on an upper surface of thesecond Light-emitting element; and a second pair of electrodes arrangedon a lower surface of the second Light-emitting element; a coveringmember covering the first Light-emitting element structure and thesecond Light-emitting element structure arranged side by side with apredetermined space interposed therebetween; a set of depressed portionscomprising a first depressed portion associated with the firstLight-emitting element structure, a second depressed portion associatedwith the second Light-emitting element structure, and a third depressedportion disposed between the first depressed portion and the seconddepressed portion; a first set of via holes connecting the firstLight-emitting element structure to a first pad and a second pad, eachof the first pad and the second pad having a second wiring and a thirdwiring; a second set of via holes connecting the second Light-emittingelement structure to the second pad and a third pad having a secondwiring and a third wiring; and a substrate comprising the set ofdepressed portions formed at a lower surface thereof, the first set ofvia holes and the second set of via holes.
 10. The light-emitting deviceaccording to claim 9, wherein a distance between one of the first set ofvia holes and one of the second set of via holes over the thirddepressed portion is larger than a shortest distance between the firstlight-transmissive member and the second light-transmissive member. 11.The light-emitting device according to claim 9, wherein a distance froman inner surface of one sidewall of the covering member to the secondlight-transmissive member proximate to the one sidewall of the coveringmember is smaller than a distance from an inner surface of one sidewallof the substrate to one of the second set of via holes proximate to theone sidewall of the substrate.
 12. The light-emitting device accordingto claim 11, wherein an outer surface of the one sidewall of thecovering member and an outer surface of the one sidewall of thesubstrate are coplanar.
 13. The light-emitting device according to claim9, wherein no depressed portion is arranged in a space between onesidewall of the substrate and one of the second set of via holesproximate to the one sidewall of the substrate.
 14. The light-emittingdevice according to claim 13, wherein no depressed portion is formedbetween the other sidewall of the substrate and one of the first set ofvia holes proximate to the other sidewall of the substrate.
 15. Thelight-emitting device according to claim 9, wherein a shortest distancebetween the first and the second light-transmissive members is smallerthan a shortest distance between the first and the second Light-emittingelements.
 16. The light-emitting device according to claim 9, furthercomprising an insulating film formed at the lower surface of thesubstrate and partially overlapped with one or more of the first, secondand third pads.